Lewmar portlight gasket sealant

[jtdums]

I am about to redo the gaskets on a pair of Lewmar "old style" portlights (gasket between glass and opening portlight).
Instructions are quite clear except for a recommendation for a "sealant" that is to be used after the gasket has been dry fit for final installation. This style of gasket has a locking protrusion to help it stay in the frame, but some mechanical bond is apparently also necessary.

My question is what sealant/adhesive?

Normally I would think 3M 4000UV, but since this is under the gasket and not exposed to light am I actually better off with silicone? Boat Life sealant? Boat life Liquid caulk?

So many choices...not enough experience.
Thank for any help.

 

[RT Firefly]

Greetings,
Mr. jt. Anything BUT silicone. Trust me. Silicone is great for house toilets but has NO place anywhere on a boat IMO.

 

[Bmarler]

Here’s what I’ve used for decades.

Amazon.com

 

[jtdums]

Here’s what I’ve used for decades.

Amazon.com

Perfect. Thank you for chiming in!

 

[more]

https://www.amazon.com/butyl-tape/s?k=butyl+tape

butyl tape

 

[jtdums]

https://www.amazon.com/butyl-tape/s?k=butyl+tape

butyl tape

It's gasket to inside of the frame. Not really a butyl tape application.

 

[more]

It's gasket to inside of the frame. Not really a butyl tape application.

what exact type?Search | Lewmar ask this guy.
i on my old Bavaria sailboat try the same, after spending money on the gasket still leaking I change all portlight to Gebo